1. Field of the Invention
The present invention relates to a dedicated short range communication (DSRC) type intelligent transport system (ITS) and, more particularly, to an apparatus and method for testing a bit error rate (BER) of the DSRC ITS.
2. Background of the Related Art
In general, an intelligent transport system has been introduced to have a smooth flow of information, without discontinuation of information, between a vehicle and a road. This is accomplished by adapting a related technology such as an electronic control and information communication system to the existing traffic system, which may include a road, a vehicle, and a signal system.
Especially, among the information communication technological fields, a radio communication technique for a bidirectional communication between the road and the vehicle is recognized as the most important field. The present invention pays much attention to the DSRC-based ITS, a radio communication technique for the next generation ITS service.
The DSRC is one of the radio communication standards between the vehicle and the road. A vehicle with an on-board equipment (OBE) and a road side equipment (RSE), installed along the roadside, communicate bi-directionally using a high-speed radio packet in a pertinent communication area, while traveling at a high speed along the roadside where the roadside equipment is installed.
FIG. 1 is a drawing illustrating the construction of a general DSRC ITS network. A general DSRC ITS network includes on-board equipment 10 mounted at a vehicle for requesting an ITS service; roadside equipment 20 installed at a streetlight or a signal light of roadside for making a bi-directional radio communication with the on-board equipment 10; a local server 30 for making a wired communication with the roadside equipment 20 to collect traffic information of a pertinent area and having a database for responding to a user's request; and a traffic information center 50 connected to the local server 30 through a communication network 40 for collecting all of the traffic information and collecting information related to other ITS networks. The local server 30 is connected to the roadside equipment by ethernet, an Asymmetric Digital Subscriber Line (ADSL), or an Integrated Services Digital Network (ISDN).
The DSRC ITS network provides various ITS services by having functions such as a traffic information collection and utilization, a forward road situation display, a bypass and signal light control, a public transportation management and guide, and a wireless charge payment of a freeway toll gate.
Like the general communication system, communication quality is very important for the DSRC ITS. Accordingly, after a manufacturer manufactures equipment (the roadside equipment or the on-board equipment) in a factory, the manufactured equipment is subjected to testing of its radio communication quality or the manufactured equipment is installed at a specific place to check its communication area or its communication quality, for which a BER test is performed. In addition, in order to check the performance of a system, a service operator may perform the BER testing at any time.
FIG. 2 is a drawing illustrating the construction of a BER testing apparatus of the ITS, in accordance with the background art. The BER testing apparatus includes a roadside equipment simulator 60, having a general function of the roadside equipment and the function of a standard signal generator. The signal generator supports an amplitude shift keying (ASK) modulation method of the ITS. The BER testing apparatus also has a testing unit 70 for controlling the strength of a test signal transmitted from the roadside equipment simulator 60 and transmitting the test signal to the on-board equipment 10. Additionally, the testing unit 70 measures a BER of the test signal feedback from the on-board equipment 10.
The testing unit 70 includes an attenuator 71 for attenuating the strength of the test signal, transmitted from the roadside equipment simulator 60, to a predetermined size and transmitting the test signal to the on-board equipment 10. A BER measuring unit 72 compares the test signal received from the roadside equipment simulator 60 and the test signal feedback from the on-board equipment 10. The operation of the BER testing unit of the ITS constructed, as described above, will now be explained.
The roadside equipment simulator 60 transmits a pre-set signal for the BER testing, that is, a test signal such as a PN9 or PN15, to the testing unit 70. The attenuator 71 of the testing unit 70 attenuates the received test signal to a size previously determined by a user and transmits it to the on-board equipment 10. The on-board equipment 10 feeds the test signal received from the testing unit 70 back to the testing unit 70. The BER measuring unit 72 compares the signal received from the on-board equipment 10 and the test signal received from the roadside equipment simulator 60 to measure the BER and displays the measured BER value on a display unit (not shown in FIG. 2).
However, the BER testing of the ITS of the background art has a shortcoming in that a high-priced testing unit is used to measure the BER. Additionally, since only the BER of the test data, such as PN9 and PN15, previously set for the BER testing of a transmission and reception signal in a radio channel environment is tested, it is not possible to test a BER of a transmitted and received frame operated in the actual ITS.
The above references are incorporated by reference herein where appropriate for appropriate teachings of additional or alternative details, features and/or technical background.